Hem 1 - Plasma and Serum Biochemistry Flashcards
functions of blood (3 categories)
-transport of substances (oxygen, carbon dioxide, nutrients, heat, waste, hormones
-regulatte (pH, temperature, hydration of cells)
-protection against (blood loss, microbes, toxins)
what is the composition of blood
normal blood separates into 45% formed elements (cells) and 55% plasma
formed elements include erythrocytes, leukocytes and thrombocutes
plasma composition
90% WATER
7% PROTEIN (primarily produced by liver)
-albumin (60%) - maintains osmotic pressure
-globulins (35%) - transport proteins/defence (alpha, beta), antibodies (gamma)
-clotting proteins (5%) - catalyze fibrin polymerization to prevent blood loss
-transiet proteins - soluble proteins from damaged and dying cells that we measure as markers. no functional role while in the bloodstream, trace levels
3% other solutes
-nitrogenous solutes (urea)
-nutrients (glucose)
-electrolytes (sodium)
-respiratory gases (oxygen)
what is the difference between serum and plasma
-when blood is collected and prevented from clotting (anticoagulants) it can be separated into cells and liquid by centrifugation. the liquid portion of unclotted blood is plasma
-when blood or plasma sites without anticoagulant, clotting factors initate clot formation and the leftover fluid is called serum
-so serum plus clotting factors is plasma and clotted plasma yields serum once its spin
what do you look for with examination of plasma (and the name for the issues)
light yellow, medium yellow, no plasma colour? concentration of bilirubin
colour changes - can see things like:
-lipidemia (wont allow for colour change so it interferes with assays)
-hemoglobinemia (red blood cells ruptured, hemoglobin leaks into plasma)
-bilirubinemia (pigments that builds up in cases of jaundice
plasma of a normal dog or cat is colourless to light yellow. yellow colour is entirely due to bilirubin
in horse and cow, plasma is medium yellow due to carotenoids present in plants
sheep, pig, water buffaloes dont show plasma colour from plant pigments (likely bc they dont digest them?)
what do we look for in plasma/serum biochemical profiles
-serum enzymes (alanine aminotransferase (ALT), lipase, amylase, alkaline phosphatase (ALP)
-normal metabolites reflecting tissue function: bilirubin, bile acids, BUN (urea)
-glucose, triglycerides and protein
-electrolytes and pH
-pO2, pCO2
-hormones
-viral proteins, antibodies
-small RNAs
serum enzymes: what are they and from where do they come
-enzymes are proteins that catalyze chemical reactions
-some are present outside cells normally and have specific functions (clotting enzymes, lipoprotein lipase) but most are inside cells
-some general enzymes are present in all cells but some are very specific for individual cell types
-most enzymes found in the serum normally reside in cells and have leaked out of cells
-they are located in the cytoplasm, mitochondria, ER, intracellular granules
principles of enzymology (what can they be used to do, what does location impact)
-serum enzymes can be used to help diagnose, monitor and prognose the disease process
-the location within the cell impacts on the release of the enzyme located into the blood
- cytoplasm = soluble, easily released
- granules = released after injury
- mitochondria = released after severe insult
- membrane = not soluble and released after severe injury
common serum enzymes and their abbreviations (7)
-ALT = alanine aminotransferase
-AST = asparate amino transferase
-SD = sorbitol dehydrogenase
-LD = lactate dehydrogenase
-ALP = alkaline phosphatase
-GGT = gamma glutamyltransferase
-CK = creatine kinase
factors affecting enzyme activity in the serum, magnitude depends on what
-cell death/injury = increased release of enzymes
-degradation, inactivation or secretion of serum enzyme = removal of enzymes from the serum
-the magnitude of increase is dependent on several factors (the tissue concentration of the enzyme, cellular location of the enzyme, amount of tissue injured, severity of tissue injury, rate of enzyme remoal from the serum)
measurement of serum enzyme activity (how do we do it, what are they affected by)
-enzyme levels often measured by looking at their activity through the use of kinetic assays (substrate changes colour when metabolized by enzyme). they measure the enzyme activity oveer time - higher enzyme concentration in blood = faster rate of substrate metabolism and stronger colour change
-in vitro the assays are affected by temp, pH, substrate concentration, cofactors, inhibitors and reagent stability = consequently the serum enzyme acttivity value may bary between laboratories
interfering factors: anticoagulants
-several are in the form of sodium or potassium salts - affect sodium and potassium levels
-heparin is often in the form of ammonium salt - affects blood urea nitrogen (BUN) results
-anticoagulants such as EDTA - affect calcium levels and enzyme activity
interfering factors: hemolysis
-can be caused by: excessive back pressure on collection syringe, forceful transfer of blood to evacuated container, rough handling, extreme temperatures
-results in increased concentraion readings for some analytes including iron, lactate dehydrogenase, potassium and total protein
characteristics of serym enzymes that make them useful clinical markers
tissue specificity, rise specifically when tissue is injured, dont rise under normal conditions, concentration, easily measured/inexpensive, half-life = intermediate duration (too short: brief detection window, too long: loss of specificity)
what is an example of a serum enzyme that is better for large animals, and dogs/cats
dogs/cats = ALT
large animals = AST
